Contact finger assembly for electric controllers



I July 5, 1932. G J LEX CONTACT FINGER ASSEMBLY FOR ELECTRIC CONTROLLERS Filed Aug. 5, 19.29

INVENTOR.

BY 7 8m 6% MM WSWMMA 9f Wad/4M ATTORNEY Patented July 5, 1932 UNITED STATES PATENT oFF cE GEORGE J. LEXA, OF MILWAUKEE,- WISGON SIN, ASSIGNOR TO HARNISCHFEGER CORPO- RATION, F MILWAUKEE, WISGONSIAT, A CORPORATION OIE WISCONSIN CONTACT FINGER ASSEMBLY FOR ELECTRIC CONTROLLERS 1 Application filed August 5, 1929. Serial No; 383,755.

This invention relates to contact finger assemblies for electric controller switches and more particularly to contact fingers of large current carrying capacity adapted for use on controllers of the drum type used in start-.

ing, stopping and regulating the speed of mo tors on cranes, excavators and the like.-

In drum controllers heretofore constructed,

faulty operation, such as excessive sparking, has resulted from misalinenient of the revolving segments of the drum and thecontact fingers. In part at least, misalinement has been due to play in the pivotal mountings for the contact fingers, this play becoming more noticeable after the relatively moving parts have become worn. The tip of the finger'being located some distance from the pivot moves considerable distance even though the play at the pivot isslight.

2' An object of the present invention is to provide a contact finger assembly in which means is provided for preventing play at the pivot from causing misalinement betweenthe tip and the revolving segments of the drum of the controller.

A further object is to provide a detachable tip for the finger which may be readily removed, reversed or replaced without the use :of special punching tools.

Another object is to reduce the movement of the pig-tail of the contact finger assembly so as to lengthen the life thereof.

Other objects and advantages reside in certain novel features of the construction, ar-

rangement and combination of parts which 7 will be hereinafter more fully described and particularly pointed out in the appended claims, reference being had to the accompanying drawing forming a part of this specification, and in which:

Figure 11 is a side view of a contact finger assembly embodying one form of the invention;

Figure 2 is a top plan view of the contact finger assembly of Figure 1; and

Figure 3 is a bottom plan view of the contact finger assembly of Figure 1.

As is well known, drum controllers include mounted contact fingers. In accordance with the present invention the contact finger assembly is shown as madeup of a pairof clamping members 1 and2, a finger 3 with its tip at and pig-tail 5 and-meansfor pivotally and yielollngly securing the finger to the clamps. f

As shown in Figures 1, and 3, the outer clamp 1 consists of a strap angled at the center and provided with outwardly projecting lugs '6 at its ends, the lugs belng provided with openings to receivebolts 8 and 9. The inner clamp 2 is also angled at its center thereby defining angularly disposed: clamping arms 2aand 26 provided at their outer ends with openings alined with those ofthe outer clamp l to receive the bolts 8 and 9. These clampsmay thus be rigidly secured upon any suitable support in the controller such as a steel bar with insulating material thereon.

The contact finger :3 consists of a sheet metal stamping bent to provide depending .fianges 10 having cars 11 at one end. For

pivot-ally mounting the finger 8 on the clamps, a hinge pin 12 is firmly secured to the cars 11, as by upsetting the ends of the pin. a The pin 12 is supported .in the bearing portion 13 of a hinge member .14 which is secured in position on the clamp 2 by bolt 9 and screw 15.

" are accurately fitted between the flanges 10 there may be considerable play at the hinge without the finger 3 tilting or moving laterally with respect to the clamps 1 and 2.

At' its forward end the filler: plate is provided with a screw threaded opening to re ceive the threaded portion of the bolt 8 which issecured in any adjusted position thereon by the lock nut 18.

Counter-clockwise movement (Figure 1) of the finger 3 about the pivot pin 12 is limited by an adjusting screw 19 carried by the finger 3 and engaging the filler plate 16. The screw 19 is provided with a square head so that it may be held in proper adjustment by a leaf spring 20 mounted on the screw 19 and the bolt 9. i

The upper end of the bolt 8 passes through slots 21 and 22- in the finger 3 and the leaf spring 20 respectively and is provided with a washer 23 which serves as an abutment for a coil spring 24. At its lower end the coil spring abuts againsts the leaf spring 20 and the finger 3 so that it tends to hold the finger down at all times. The tension in this spring may be varied by adjusting the position of the bolt 8 on the filler plate 16. Clockwise movementof the finger 3 is limited by engagement of the bolt 8 with the left end of slot 21. r

As heretofore generally constructed, the end of the finger has been provided with a tip of copper or the like, this tip being riveted or otherwise permanently secured thereto. In accordance with the present invention, the tip t of copper or the like is detachably connccted to the finger by means of bolts 25 screw threaded into openings in the shank 26 of the tip. The outer portion of the tip is somewhat cylindrical in shape so as to provide two distinct wearing surfaces as shown at 27 and '28. The tip may thus be readily reversed or replaced without the use of special tools. The useful life of the finger is thus lengthened.

For shunting the hinge joint, a pig-tail 5 is provided. The pig-tail may be of any suitable construction, the one shown consisting of the usual woven stranded conductor with terminal clips secured to the ends. thereof. The upper terminal clip may be riveted to the finger 3 as shown at 29 while the lower clip is preferably provided with openings to receive the clamping bolts 9 and an auxiliary securing screw 30. These bolts also clamp the terminal 31 of the conductor 32 in position, as shown in Figure 1.

It will be noted that the pig-tail is located in substantially vertical alinement with the hinge joint so asto be bent only a slight amount upon movement of the finger.

lVhile only one embodiment of the invention has been shown anddescribed herein it is obvious that many changes may be made in the construction or arrangement of the parts without departing from the spirit of the invention or the scope of the annexed claims.

The invention claimed is:

1. A contact finger assembly for electric controllers comprising'a clamping member including angularly disposed arms defining an interior angle adapted to receive an element of a supporting structure, a finger hingedly connected to the exterior face of one of said arms and overlying the other of said arms, said finger including guide flanges operatively engaging the side faces of the other arm whereby to prevent lateral displacement of the finger.

2. A contact finger assembly for electric controllers comprising a clamping member including angularly disposed arms defining an interior angle adapted to receive an element of a supporting structure, a finger member, a hinge depending from one end of the finger member and connected to the exterior face of one of said arms, the finger member extending therefrom in overlying superposed relation to the other arm, and longitudinally extending guide flanges depending from the finger member and operatively engaging the side faces of said other arm whereby to prevent lateral displacement of the finger.

3 A contact finger assembly for electric controllers comprising a clamping member including angularly disposed arms defining an interior angle adapted to receive an element of a supporting structure, a finger memher, a hinge depending from one end of the finger member and connected to the exterior face of one of said arms, the finger member extending therefrom in overlying superposed relation to the other arm, a filler plate secured to said other arm and lying between it and the finger member, longitudinal guide flanges depending from the finger member and operatively engaging the side faces of said filler plate and said other arm whereby to prevent lateral displacement of the finger.

4'. A contact finger assembly for electric controllers comprising a finger supporting member including angularly disposed arms each having exterlor angularly related. faces, a finger element mounted on the exterior face of one of the arms of the support overlying the exterior face of the other arm thereof, 1ongitudinal guide flanges carried by the finger member operatively engaging the side faces of saidother arm, spring means for biasing the finger in one direction, and stop members for limiting the pivotal movement of the finger, said guide flanges ofthe finger member and the side facesof said other arm having sufficient contact area to insure the flanges maintaining guiding contact with said faces throughout substantially the entire length of'the ar-mwithin the range of movement permitted by said stop members.

In witness whereof, I hereto afiix my signature.

GEORGE J. LEXA. 

